The present invention relates to a support for use in thermally developable silver halide photothermographic materials and thermally developable silver halide photothermographic materials using the same, and in particular to a surface treatment method suitable for silver halide photothermographic materials, support prepared by the method thereof and silver halide photothermographic materials having a support which has been subjected to a surface treatment, thereby exhibiting superior adhesion to the thermally developable silver halide light sensitive layer.
There are known a variety of photosensitive materials having on a support a light sensitive layer, forming images upon imagewise exposure to light. Of these, techniques of thermally developable silver halide photographic materials, i.e., photothermographic materials are cited as a system suited for environmental protection and a simple image forming means.
Silver halide photothermographic materials are detailed in U.S. Pat. Nos. 3,152,904 and 3,487,075; Morgan xe2x80x9cDry Silver Photographic Materialxe2x80x9d and D. H. Klosterboer, xe2x80x9cThermally Processed Silver Systemsxe2x80x9d (Imaging Processes and Materials, Neblette, 8th Edition, edited by J. M. Sturge, V. Walworth, and A. Shepp, page 279, 1989), etc.
Such a photothermographic material forms images, after exposure, through thermal development, which usually comprises a reducible silver source (e.g., organic silver salt), a catalytically active amount of photocatalyst (e.g., silver halide), a reducing agent and optionally an image toning agent for modifying image color, which are dispersed in an organic binder matrix. The photothermographic materials are stable at ordinary temperature and forms silver upon heating, after exposure, at a relatively high temperature (e.g., 80 to 150xc2x0 C.) through an oxidation-reduction reaction between the reducible silver source (which functions as an oxidizing agent) and the reducing agent. The oxidation-reduction reaction is accelerated by catalytic action of a latent image produced by exposure. Silver formed through reaction of the reducible silver salt in exposed areas provides a black image, which contrasts with non-exposed areas, leading to image formation. This reaction process proceeds without supplying a processing solution such as water. Such silver halide photothermographic materials are consistent with the recently increasing requirement for simplified processing and environmental protection.
In almost silver halide photothermographic materials, organic solvent-based coating solutions are usually coated and dried to form a light sensitive layer. For example, the use of an organic solvent-based coating solution comprised of toluene and a methyl ethyl ketone solution of polyvinyl butyral is described in U.S. Pat. No. 5,415,993. Further, coating solutions containing 2-butanol or methanol as an organic solvent are employed to form a light sensitive layer. Organic solvent-based coating solutions have to be coated so that a photothermographic light sensitive layer cannot be formed on the support subbed for use in conventional silver halide photographic materials. Thus, a photothermographic silver salt light sensitive layer is directly coated on a support having no sublayer.
In such a case, however, it was proved that there are problems with respect to adhesion between the support and the photothermographic light sensitive layer. In conventional tape-pull tests, it was judged that sufficient adhesion was achieved. However, it was further found that delamination was caused when a roll film having a photothermographic light sensitive layer and a backing layer is cut to a given size using a cutting machine such as a trimmer or a guillotine cutter.
In view of the foregoing problems, one aspect of the present invention concerns a photothermographic material exhibiting superior adhesion property and causing no delamination when being cut with a cutting machine.
It is an object of the present invention to provide a treatment method of a support, thereby leading to prevention of delamination between the support and the photothermographic light sensitive layer, the support and the photothermographic material.
The object of the invention can be accomplished by the following constitution:
(1) a surface treatment method for enhancing hydrophobicity of the surface of a film support, the method comprising subjecting at least one side of the support surface to a plasma discharge treatment in a gas phase atmosphere introduced under atmospheric pressure or pressure proximal, which comprises an inert gas containing argon or helium and a reactive gas containing a hydrocarbon gas or fluorinated hydrocarbon gas, while the support being continuously transported;
(2) the surface treatment method described in (1), wherein the inert gas contains argon of not less than 50% by pressure and further containing helium of less 40% by pressure;
(3) the surface treatment method described in (1) or (2), wherein the plasma discharge treatment is conducted in a gas phase containing not more than 750 ppm of oxygen;
(4) the surface treatment method described in (3), wherein oxygen is not more than 600 ppm;
(5) the surface treatment method described in (4), wherein oxygen is not more than 200 ppm;
(6) a support having thereon a layer formed by coating a organic solvent-based solution, wherein at least one surface of the support has been subjected to a plasma discharge treatment under atmospheric pressure or pressure proximal thereto in a gas phase comprising an inert gas containing argon or helium and a reactive gas containing a hydrocarbon gas or fluorinated hydrocarbon gas, while the support being continuously transported;
(7) the support described in (6), wherein the support surface which has been subjected to the plasma discharge treatment exhibits a larger contact angle between the support and methylene chloride than a support which has not been subjected to the treatment;
(8) the support described in (6), wherein the support surface which has been subjected to the plasma discharge treatment exhibits a larger contact angle between the support and water than a support which has not been subjected to the treatment;
(9) a silver halide photothermographic material comprising a support having a light sensitive layer at least one side of the support, which has been subjected to a plasma discharge treatment in a gas phase atmosphere introduced under atmospheric pressure or pressure proximal, which comprises an inert gas containing argon or helium and a reactive gas containing a hydrocarbon gas or fluorinated hydrocarbon gas.